1. Field of the Invention:
This invention relates to measurement apparatus and, more particularly, to measurement apparatus utilizing a sonar head for sending and receiving sonar signals and for using the sonar signals for measuring relatively small distances very accurately.
2. Description of the Prior Art:
Obviously, there are various ways of measuring work in terms of relatively small distances. To begin with, measurement of small distances is typically made from a relatively flat surface. Mechanical elements may be used to measure upwardly from the flat surface to the top of the work to be measured. Such measurements are typically made by mechanical elements, such as measuring and the like.
For measuring horizontal distances, laser beams may be used for measuring both small and large distances. A laser beam, typically a pulse laser beam, is reflected from a target, and the length of time between the sending and the receiving of the laser pulses is measured to determine the distance.
For measuring the thickness of a work, such as the thickness of a film, relatively sophisticated equipment is generally required. Obviously, the utilization of mechanical elements for measuring relatively thin film, in terms of four or five or six decimal places for centimeters, millimeters, or inches, or the like, mechanical measuring apparatus is obviously incapable of providing accurate results. Hence, it is typically necessary to use some type of electronic measuring apparatus or measuring apparatus that utilizes some type of energy beam, in which the energy is reflected from the target work and is compared with a reference figure. Such apparatus is generally relatively expensive and is relatively complicated in terms of usage and is relatively time consuming in terms of the time required to make a measurement.
The apparatus of the present invention utilizes sonar energy, and is relatively inexpensive to use, relatively fast in providing the desired information, and is relatively easy to use. A microcomputer is utilized with the apparatus of the present invention to keep track of the distance a stepper motor moves in moving the sonar head to provide a predetermined distance from a target which is equal to the predetermined reference or calibration distance originally established by the apparatus.